Device for varying the volute and throat of a centrifugal pump

ABSTRACT

A device for varying the discharge area perpendicular to the normal flow in the passage in a centrifugal pump comprising a coiled member.

1 Sept. 11, 1973 111M States Pafiem 1191 Pollak e1 al.

2,144,417 1/1939 Schneible........................ 1,914,919 6/1933 Heermans.... 1,144,719 6/1915 1 DEVICE FOR VARYTNG THE VOLUTE AND THROAT OF A CENTRIFUGAL PUMP [76] Inventors: Henry M. Pollak; Robert S. Pollak,

both of c/o American Machine and Tool Co.

4 3 5. 8% N2 mw m m m m L D. P m A R m r S m W C T NH mil m Inc. Fourth Ave. and Spring St., Royersford, Pa. 19468 Nov. 15, 1971 [22] Filed:

Ifrjm a FJrg r jner- Henry F. Raduazo Attorney-Arthur H. Seidel, Joel S. Goldhammer et Appl. No.: 198,928

ABSTRACT [52] 11.8. 415/121, 415/206, 415/219 B [51] lint. F0411 17/00, F04d 29/44 [58] Field of Search............ 415/121, 219 B, 219 C;

References Cited UNITED STATES PATENTS 3,048,117 Franzen et a1. 415/219 B 12 Claims, 4 Drawing Figures DEVICE FOR VARYING THE VOLUTE AND THROAT OF A CENTRIFUGAL PUMP DISCLOSURE This invention relates to centrifugal pumps and more particularly to a means for varying the size of the discharge passage of a centrifugal pump.

Centrifugal pumps is a class of hydraulic equipment well known in industry. They may be of single volute or multiple volute design. They have been the subject of creases and the power input required to maintain that pressure head is reduced.

Thus, under some conditions, it is desirable to be able to selectively vary the area perpendicular to the normal flow in the discharge passage on a centrifugal pump. Additionally, the area perpendicular to the normal flow in the discharge passage may have to be reduced because it has been worn to a diameter which is larger than desired. Discharge passages have been reduced in the past by employing valves of various types which are operative to close the discharge passage. The obvious disadvantage of using a valve is that the high degree of turbulence caused by the liquid encountering the valve vastly reduces the pressure head which the pump is capable of achieving.

Other attempts is dealing with this problem have included the use of liners which may be bolted or otherwise fastened to the interior of a pump discharge passage. The obvious difficulty with such an arrangement is that each size pump must have its own liner. Additionally, the discharge passages on these pumps must be substantially straight in order for the liner to be received therein.

Thus, in pumps where the discharge passage is curved or not readily accessible, liners of the type known heretofore have not been usable. A particular problem is realized in pumps having multiplefvolutes where the discharge passage may extend halfway around the pump casing.

Accordingly, it is an object of this invention to provide a new and unobvious means for selectively reducing the area perpendicular to the normal flow in a discharge passage in a centrifugal pump.

Generally, the inventionrelatesto a means for selectively reducing the area perpendicular to the normal flow in a discharge passage in a centrifugal pump of the type having a volute including a discharge passage.

Additionally, the invention relates to the method of selectively reducing the are perpendicular to the normal flow in a discharge passage in a centrifugal pump comprising thestep of inserting an elongated coiled member into the discharge passage.

For the purpose of illustrating the invention, there is shown in the drawings a form which is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown and wherein:

v both tapered.

FIG. 1 is a sectional view taken through one type of centrifugal pump and showing the manner in which the present invention is utilized.

FIG. 2 is a view similar to FIG. 1, however, showing a different type of centrifugal pump.

FIG. 3 is an enlarged view of a coiled member constructed in accordance with one of the forms of the invention.

FIG. 4 is a view similar to FIG. 3, however, showing still a different coiled member.

Referring now to FIG. 1, the centrifugal pump is shown having a casing 10 which defines a volute 12. An impeller 14 is mounted for rotation about a hub 16. The impeller rotates in the direction indicated by the arrow so that liquid which enters the pump near the impeller hub 16 is hurled thereby into the volute.

The fluid leaves the pump by passing through throat 18 at one end of discharge passage 20 and through discharge outlet 22 at the other end of the discharge passage. A flange 24 may be supported by the casing 10 immediately outside the discharge outlet 22. The purpose of the flange is to permit the discharge outlet of the pump to be connected to a suitable conduit.

In accordance with the present invention, the area perpendicular to the normal flow in the discharge passage 20 can be selectively varied by the insertion of a coiled member 26. As seen in FIG. 1, the coiled member is tapered so that one end is larger than the other. It is hollow with a flow-passage 27 extending therethrough. The outside diameter of the coils at the smaller end of the coiled member, however, is slightly larger than the diameter of the throat. Thus, when the coiled member is inserted into the discharge passage, the inner most coils 28 are prevented from entering the volute by virtue of their bearing against the throat. The remaining coils lie along the interior surface 31 discharge passage. The coils at the other end 29 of the coiled member are constrained within the discharge passage by a suitable constraining means.

As seen in the embodiment of the invention shown in FIG. 1, the longitudinal axis of the coiled member is straight in that it is coincident with the longitudinal axis of the discharge passage 20. Additionally, the coils of the coiled member are of such size that theinside wall 30 of the coiled member and itsoutside wall 34 are It is apparent that the coiled member 26 canbe quickly and easily inserted and removed from the discharge passage in response to various performance characteristics. Because the coiled memberis comprised of a number of coils, it is not confined to any particular configuration but can-take theshape of the discharge passage into' which it is inserted without changing the internal area formed by the coils;

Thus, in FIG. 2 a casing 40 for a second centrifugal pump is shown. The casing includes a volute 42 which defines a throat 46 at one end of a discharge passage 48 which terminates in a discharge outlet 50.

A flange 52 is formed at the discharge'outlet. A coiled member 54 similar to that described in connection with FIG. 1, is insertable within the discharge passage 48. Significantly, discharge passage 48 is curved so that a rigid liner could notbe received therein. I-Iowthat the coiled member cannot enter the volute. At the other end of the coiled member, the last few coils 56 are enlarged so that they may be received within a recess 57 formed within the aforementioned flange 52. The end coils 56 bear against a ledge 59 formed by the recess. The coiled member is hollow with a flow passage 61 extending therethrough. A threaded fitting 58 having a flange 60 to be connected to aforementioned flange 52 may be provided to cooperate with flange 52 to confine the large coils 56 within recess 57.

It is apprent that by careful selection of the coiled member which is to be inserted within the discharge passage, the performance characteristics of the pump can be controlled to a great degree. Thus, the coiled members shown in FIGS. 1 and 2 are comprised of wire that is of constant diameter. While round wire may be used, it is also within the scope of this invention to use wire of any convenient cross section. Further, it is also within the scope of this invention to form the coiled member from a tapered member.

In FIG. 3, a modified coiled member 60 having tapered inner and outer walls 62 and 64 is shown. Significantly, the two walls are tapered in different degrees. This follows from having the coiled member made from a tapered member. The member may have any cross section although a rounded cross section is illustrated. Thus, when the coiled member is inserted in a discharge passage, the rate of expansion of the discharge passage between the throat and the discharge outlet will be less than if the coiled member were comprised of a member of constant cross section.

Further, as seen in FIG. 4, a further modified coiled member 70 having enlarged coils 72 near its midportion and smaller coils 74 at its ends could also be charge passage, said member being comprised of a plurality of coils so that it takes the shape of said discharge passage, and said member is hollow and has a flow passage therethrough.

2. A centrifugal pump as defined in claim 1 wherein said coiled member comprises a plurality of coils for lying along the interior surface of said discharge passage so that said coils are operative to reduce said area of said discharge passage when said coiled member is disposed in said discharge passage.

3. A centrifugal pump as defined in claim 2 wherein said throat area is less than the area defined by the outside diameter of the coils at one end of said coiled member, retaining means coupled to said casing adjacent said discharge opening, and said coiled member is to be confined in said discharge passage between said throat and said discharge opening.

4. A centrifugal pump as defined in claim 2 wherein the outside wall of said coiled member is tapered.

5. A centrifugal pump as defined in claim 2 wherein both the inside wall and the outside diameter of said coiled member are tapered to different degrees.

6. A centrifugal pump as defined in claim 2 wherein at least some of the coils of said coiled member have different diameters than the other coils.

7. A centrifugal pump as defined in claim 6 wherein said coils having the largest diameter are intermediate the ends of said coiled member.

8. In a centrifugal pump of the type comprising a casing that defines a discharge passage having a throat and a discharge opening, the method of selectively reducing the area perpendicular to the normal flow in said disused to further alter the performance characteristics of a centrifugal pump. Thus, the velocity and pressure head of the fluid leaving the discharge outlet of the pump could be controlled within wide limits.

it should be noted that in each instance, a spring could be substituted for the coiled members without altering the affect or achievement of the invention.

While this invention has been described with reference to a number of embodiments thereof, it is apparent that many other forms of embodiments will be obvious to those skilled in the art in view of the foregoing description. Thus, the scope of the invention should not be limited by the foregoing description, rather, only by the scope of the We claim:

l. in a centrifugal pump of the type comprising a casing that defines at least one discharge passage, said discharge passage having a throat and a discharge openin g, the improvement comprising, means for selectively reducing the area perpendicular to the normal flow in said at least one discharge passage, said means comprising an elongated member to be disposed in said disclaims appended hereto.

charge passage comprising the steps of providing an elongated member, said member being comprised of a plurality of coils so that it takes the shape of said discharge passage and being hollow with a flow passage therethrough, the coils at one end of said member having an outside diameter greater than the diameter of said throat, inserting said member into said discharge passage until said one end engages said throat, permitting said coils to lie along the interior surface of said discharge passage to reduce said area, and confining the other end of said member to constrain it within said discharge passage.

9. A centrifugal pump as defined in, claim 8 wherein the outside diameter of said coiled member is tapered. 10. A centrifugal pump as defined in claim 8 wherein both the inside diameter and the outside diameter of said'coiled members are tapered to different degrees.

11. A centrifugal pump as defined in claim 8 wherein at least some of the coils of said coiled member have intermediate the ends of said coiled member.

i i i i i 

1. In a centrifugal pump of the type comprising a casing that defines at least one discharge passage, said discharge passage having a throat and a discharge opening, the improvement comprising, means for selectively reducing the area perpendicular to the normal flow in said at least one discharge passage, said means comprising an elongated member to be disposed in said discharge passage, said member being comprised of a plurality of coils so that it takes the shape of said discharge passage, and said member is hollow and has a flow passage therethrough.
 2. A centrifugal pump as defined in claim 1 wherein said coiled member comprises a plurality of coils for lying along the interior surface of said discharge passage so that said coils are operative to reduce said area of said discharge passage when said coiled member is disposed in said discharge passage.
 3. A centrifugal pump as defined in claim 2 wherein said throat area is less than the area defined by the outside diameter of the coils at one end of said coiled member, retaining means coupled to said casing adjacent said discharge opening, and said coiled member is to be confined in said discharge passage between said throat and said discharge opening.
 4. A centrifugal pump as defined in claim 2 wherein the outside wall of said coiled member is tapered.
 5. A centrifugal pump as defined in claim 2 wherein both the inside wall and the outside diameter of said coiled member are tapered to different degrees.
 6. A centrifugal pump as defined in claim 2 wherein at least some of the coils of said coiled member have different diameters than the other coils.
 7. A centrifugal pump as defined in claim 6 wherein said coils having the largest diameter are intermediate the ends of said coiled member.
 8. In a centrifugal pump of the type comprising a casing that defines a discharge passage having a throat and a discharge opening, the method of selectively reducing the area perpendicular to tHe normal flow in said discharge passage comprising the steps of providing an elongated member, said member being comprised of a plurality of coils so that it takes the shape of said discharge passage and being hollow with a flow passage therethrough, the coils at one end of said member having an outside diameter greater than the diameter of said throat, inserting said member into said discharge passage until said one end engages said throat, permitting said coils to lie along the interior surface of said discharge passage to reduce said area, and confining the other end of said member to constrain it within said discharge passage.
 9. A centrifugal pump as defined in claim 8 wherein the outside diameter of said coiled member is tapered.
 10. A centrifugal pump as defined in claim 8 wherein both the inside diameter and the outside diameter of said coiled members are tapered to different degrees.
 11. A centrifugal pump as defined in claim 8 wherein at least some of the coils of said coiled member have different diameters than the other coils.
 12. A centrifugal coiled member as defined in claim 11 wherein said coils having the largest diameter are intermediate the ends of said coiled member. 